The present disclosure relates to check valves. More specifically, the present disclosure relates to multi-flapper check valves for use in environmental control systems.
Environmental control systems in aircraft condition air for delivery to an aircraft cabin. Conditioned air is air at a temperature, pressure, and humidity desirable for aircraft passenger comfort and safety. At or near ground level, the ambient air temperature and/or humidity is often sufficiently high that the air must be cooled as part of the conditioning process before being delivered to the aircraft cabin. At flight altitude, ambient air is often far cooler than desired, but at such a low pressure that it must be compressed to an acceptable pressure as part of the conditioning process. Compressing ambient air at flight altitude heats the resulting pressurized air sufficiently that it must be cooled, even if the initial ambient air temperature is very low. Thus, under most conditions, heat must be removed from air by the environmental control system before the air is delivered to the aircraft cabin. Environmental control systems can include air cycle machines that include a compressor section and at least one turbine section that can be used to cool and pressurize the air.
Environmental control systems include check valves positioned throughout the system to allow air to flow in a first direction through the environmental control system and to prevent the air from flowing in a second direction through the environmental control system. In a closed position, check valves prevent air from moving through the environmental control system. Once the pressure of the air in the system reaches a certain level, the check valve opens to allow air to flow through the system. In this manner, check valves can regulate how air moves through the environmental control system based on the pressure of the air in the system.